Forged pistons?

mgbv8 · Post by **mgbv8** » Fri Aug 10, 2007 7:16 pm

Good info Stevie. I thought the narrow band ubits were ok for an indication. I normally set the car to run in the middle of the Rich band on the display.
Thanks mate.

stevieturbo · Post by **stevieturbo** » Fri Aug 10, 2007 7:27 pm

They are ok as rich/lean indicators.

If you are intent on using one for tuning, at least use a voltmeter, or something you know for sure is a target that is safe

Generally on a turbo car, 0.85-0.9v is acceptable. But again, heat, pressure, and all sorts can massively affect the voltage output for these things.

So you really need to be fully aware of thier shortcomings, before you even think about using one for tuning.

For the price, widebands arent expensive.

Buy a LC-1 from Bill, and use something like this for a display

http://cgi.ebay.co.uk/ON-OFF-BACKLIT-BL ... dZViewItem

Cheapest wideband setup you will get.

Configure the LC-1 to output 1.0v at 10.0:1 AFR, and 2.0v at 20.0:1 AFR ( Innovates own display does this too ), then play with the dip switches on the rear of the LCD display, until the decimal point is reading your AFR's correctly

Also confirm this on the volt display by flatlining the LC-1's output at say 1.2v ( 12.0:1 AFR )...an important number, as its in the general target area you will be aiming for.

Also, might be worth slowing the LC-1's output from instant, to say 6 times per sec...the display aint that fast, but it is sufficiently fast to tune with.

I found the blue display very bright at night. The green or red are slightly duller.

mgbv8 · Post by **mgbv8** » Fri Aug 10, 2007 7:33 pm

WOW!
Good info again mate.Thanks>
I'll start investigating when I get the engine stripped over this weekend.
Perry

Paul B · Post by **Paul B** » Sat Aug 11, 2007 12:28 pm

mgbv8 wrote:WOW!
Good info again mate.Thanks>
I'll start investigating when I get the engine stripped over this weekend.
Perry

Have you considered some sort of ceramic coating for your pistons? I've heard good things about it, and I'd guess it could be done to standard piston to keep the heat at bay - and the price down.

stevieturbo · Post by **stevieturbo** » Sat Aug 11, 2007 4:45 pm

With correct tuning, no coatings are needed.

mgbv8 · Post by **mgbv8** » Sat Aug 11, 2007 8:14 pm

So I understand Stevie.
I've just taken the left head off, and I've also blown the rings on number 7, loads of oil around in the bore, but no melting.
Number one has a large piece missing like last time. Same place as last time too. Top of the bore, but a lump of the top ring is missing too. About 1.5 inches long. There a gouges in the head where its been bouncing around inside, there is lots of ally spray coating in the exhaust valve chamber, and some witness marks where the broken ring has passed into the exhaust chamber. I've measured the valve height and its ok. I'm hoping there is not too much damage to the valve faces, but its not much of a job to sort that anyway is it. If anyone wants to give me their email, I will pass on some pics to post up.
I'll have the other head off sometime tomorrow with a bit of luck. Gill wants me to do some painting type stuff in the lounge. I'm going to ply her with wine tonight so she sleeps in tomorrow. That way I can get into the garage before she wakes up. Fiendish plan eh Carothers!!!

stevieturbo · Post by **stevieturbo** » Sat Aug 11, 2007 9:57 pm

Cylinder pressures might have just broke the rings. Or detonation....

send pics to stevieturbo at yahoo dot com, or hotmail etc etc

mgbv8 · Post by **mgbv8** » Fri Aug 17, 2007 7:25 pm

Pics sent Stevie.
Thanks
Perry

stevieturbo · Post by **stevieturbo** » Fri Aug 17, 2007 11:46 pm

no sign of any emails ??

mgbv8 · Post by **mgbv8** » Sat Aug 18, 2007 9:07 am

Hmm?
I'll try again later.

stevieturbo · Post by **stevieturbo** » Sat Aug 18, 2007 3:57 pm

Pretty major meltdown.....seriously lean IMO.

Get that wideband !!!!!!!!!!!1

mgbv8 · Post by **mgbv8** » Sat Aug 18, 2007 7:15 pm

Yep!
I thought she might have been a bit lean too Stevie.
The last melted piston was only a fraction of the one in the pic.
It didnt expose the top ring, let along break a bit off to cause the shrapnell damage. Luckily, the bore is spot on, but the head suffered some simialr gouging marks.
Next time out with this engine I will up the fuel jet a tad.

Thanks for posting the pic mate.

Boosted LS1 · Post by **Boosted LS1** » Wed Aug 22, 2007 8:14 pm

You could try retarding the nitrous shot so it arrives a bit later and then if you want, increase the shot volume.

Mike.

mgbv8 · Post by **mgbv8** » Thu Aug 23, 2007 5:51 pm

The car runs ok on a 150 shot. The last two occasions where I melted pistons were when I was trying to set up a 200 shot.
I had the nitrous set to deliver 35% at launch, then build to 200 over 4.5 seconds.

It was when I incraesed the start to 40% and reduced the build time to 3.5 seconds that she let go.

I'm still running lean so I'll need to increase the fuel for the next try.

mgbv8 · Post by **mgbv8** » Thu Aug 23, 2007 5:54 pm

Also, the rev limiter cut in at 3/4 track. It doesnt normally start to cut in until I'm just over the line.
So I know it was a quick run. I just need to remember to disable the limiter.